Water can be made to diffuse against the water content gradient in starchy foods

In this paper, the idea of making water molecules move against their concentration gradient was proved to be possible by experiment. Simultaneous heating and cooling treatment was applied to a slab of wheat flour dough that initially had uniform water content throughout. The dough slab was heated to 90 °C on one side and cooled with iced water on the other side. After the treatment, the change of the water content profile across the slab was observed using magnetic resonance imaging, while the slab was left at room temperature. It was found that water migrated from the cooled side to the heated side, and the migration continued against their concentration gradient. This water migration behavior was successfully simulated by a multiphase multilayer model in which partition equilibrium based on ceiling water content was assumed at the boundary between the layers adjacent each other. Inside each of the layer, on the other hand, water diffusion was calculated using Fick’s diffusion equation.